What is mallet finger (injury to the extensor tendon of the finger)?

From the Guidelines

Mallet finger is an injury to the extensor tendon of the finger, specifically at the distal interphalangeal joint, which can be diagnosed with radiographs to detect fracture fragments or bony avulsion 1. Mallet finger occurs when the extensor tendon is damaged, either by tearing or when the tendon is pulled away from the bone, often from a direct blow to the fingertip or forceful bending.

• The diagnosis of mallet finger involves radiographic examination to detect fracture fragments or bony avulsion at the insertion of the extensor mechanism of the finger to the distal interphalangeal joint 1.
• Treatment typically involves continuous splinting of the fingertip in a straight position for 6-8 weeks, keeping the splint on at all times, even during bathing.
• The splint should hold only the end joint (DIP joint) straight while allowing the middle joint to bend, and surgery is usually only necessary if there's a large bone fragment or the joint is misaligned, such as palmar displacement of the distal phalanx or an interfragmentary gap of >3 mm 1. After splinting, gentle exercises help restore movement, but patients should avoid forceful bending for several more weeks.
• Without proper treatment, mallet finger can lead to permanent deformity and arthritis, but even with treatment, some permanent drooping may remain, although function usually returns to normal. The goal of treatment is to prevent long-term morbidity and mortality associated with untreated mallet finger, such as chronic pain, decreased range of motion, and decreased quality of life 1.

From the Research

Definition and Causes of Mallet Finger

• Mallet finger is a fingertip deformity where the distal interphalangeal joint (DIPJ) of the affected digit is held in flexion, unable to extend the distal phalanx actively 2.
• The deformity is typically a consequence of traumatic disruption to the terminal extensor tendon at its insertion at the proximal portion of the distal phalanx or slightly proximally at the level of the DIPJ 2.
• Common mechanisms of injury include sport activities causing a direct blow to the finger, low energy trauma while performing simple tasks, or crush injuries from getting the finger trapped in a door 2.

Symptoms and Diagnosis

• Patients typically present with a history describing the event of injury with a typical mallet deformity 2.
• The DIPJ can be passively extended, but this extension of the joint cannot be maintained once the passive extension is stopped 2.
• Mallet finger is diagnosed clinically, but an X-ray should always be performed to rule out any bony avulsion or fracture 3.

Treatment Options

• The majority of closed mallet splints are Doyle type I, which can be managed non-surgically with external splints, worn full-time to keep the fingertip straight until the tendon injury or fracture heals 2.
• Surgical techniques are considered for other types of mallet injuries, including closed reduction and Kirschner wire fixation, open reduction and internal fixation, reconstruction of the terminal extensor tendon, and correction of swan neck deformity 2.
• A direct tendon suture technique using the distal interphalangeal (DIP) joint open approach has been shown to be effective in treating tendinous mallet finger injury 4.
• Percutaneous tenodermodesis is an office-based procedure that provides joint reduction and prevents joint movement during the immobilization period 5.
• Surgical fixation is still indicated in certain conditions, such as open injuries, avulsion fracture involving at least one third of the articular surface, and failed splinting treatment 6.